That's actually a choice you're going to have to make yourself.

Here are some prediction tools that may or may not work.

http://mjperry.blogspot.com/2010/08/buy-now-or-wait-check-airfare.html

http://www.crunchbase.com/company/farecast

Best thing to do is to signup to your airline's frequent flyer programme and subscribe to their mailing list. That way, you'll receive news of special offers as they appear.

I'd suggest subscribing to Delta, United, Lufthansa, SAS and Air France since there aren't any direct flights to Copenhagen from Atlanta.

Signing up to an airline's frequent flyer programme often means you can choose your meals in advance such as vegetarian menus for example, and select your seats earlier.

Lufthansa flies to Atlanta via Frankfurt, Germany and Air France, via Charles de Gaulle airport.

Lufthansa's US site: http://www.lufthansa.com/us/en/homepage

Air France US site: http://www.airfrance.us/cgi-bin/AF/US/en/common/home/flights/ticket-plane.do

We have flown SAS twice in the past 18 months, via Copenhagen. We have enjoyed the flights and service. They often have sales so sign up for emails and join FF club. www.flysas.com

We also participated in their partnership with Optiontown to get low cost upgrades. We have been successful with upgrades to Business on all 4 transatlantic flights for a fraction of what it normally costs. www.optiontown.com

We flew via Dulles on one trip and O'Hare on the other. They also fly out of Newark.

Nobody, including the airlines, can be sure what the rates will be when you want to go. Sites such as www.kayak.com or orbitz.com will give you a range of combinations for airlines and their fares as available now; you can follow up with the airlines themselves. Or look at www.itasoftware.com, which provides computer services for many (not all) airlines but doesn't sell tickets. To be more adventurous, www.skyscanner.com includes some of the budget European lines that the others don't cover.

@DebitNM - would you mind sharing what you paid for one of your upgrades?

I think it is best to monitor flight prices via Kayak or other sites which will send you daily or weekly price checks for the route (all airlines flying the route will be priced). Once you see the fare hit a price that you are comfortable with, grab it. May is generally the start of shoulder or even high season so the fare may be higher than they are for the proceeding months. Basically its like playing roulette though -- no telling what the airlines will do price wise.

it was approx $462 per person per transatlantic flight. A bargain compared to the business class fare.